deflektion

Deflektion (German: Deflektion; English: deflection or deflexion) denotes the deviation of a moving object, beam, or signal from its original trajectory. It describes how external forces, fields, or media alter motion or path. It is used across physics, engineering, and related fields.

In structural engineering, deflection is the displacement of a point on a structural element under load. It is usually small relative to dimensions, and is critical for serviceability. The deflection y(x) of a beam is found with differential equations; for a simply supported beam with a uniform load, the maximum deflection is δ_max = 5 q L^4 / (384 E I).

In particle physics and electromagnetism, deflection describes the bending of a charged particle's trajectory in electric or magnetic fields. In a uniform magnetic field, the path is circular with radius R = p/(qB); over a path length L, the deflection angle is approximately θ ≈ L/R = q B L / p. In electric fields, similar relations apply, with the deflection proportional to the charge, field strength, and travel path.

In optics and astronomy, deflection refers to bending of light rays due to refraction at interfaces or gravitational lensing. It can be described by an angular deflection measured in radians or degrees; gravitational deflection by massive bodies is a classic observable predicted by general relativity.

Etymology and usage: in German, Deflektion is the standard technical term; in English, deflection or deflexion is common, with similar meanings across disciplines.